INTERNATIONAL J OURNAL OF M ULTIDISCIPLINARY S CIENCES AND ENGINEERING , VOL . 6, NO. 9, S EPTEMBER 2015
Design and Optimization of Pelton Wheel Turbine
for Tube-Well
Faiz Ahmed Meeran1, Muhammad Arslan2, Ali Raza Mansha3 and Aamir Sajjad4
1
Karachi Institute of Power Engineering
2
Mechanical Engineering Department, UET, Lahore
3
Mechanical Engineering Department University of Sargodha
4
Mechanical Engineering Department, RCET Gujranwala
1
engineerfaizi8@gmail.com, 2arslan.unique@gmail.com, 3engralirazamansha76@gmail.com, 4aamir.sajjad481@gmail.com
Abstract– In this work a Pelton wheel was designed and
optimized which can be installed on tube well and can work as
portable power generation system. This work is done by keeping
in mind the current energy scenario of Pakistan. After designing,
optimization is made by changing different parameters i.e.,
number of buckets, number of jets, diameter of jet, angle of
deflection and jet ratio. And different characteristics curves are
plotted and compared to select parameters giving maximum
efficiency. By installing this turbine on ordinary (14 cm outlet
pipe diameter) tube-well, the approximated output power is 2.8
KW. This work is done because of accountable potential at tube
wells in Pakistan. Keeping in mind the compactness, bulkiness,
cost and portability of turbine the fly-wheel was accommodated
at the circumference of the wheel.
lights. Here is a graph from which we can estimate the
potential of energy sources requires by the tube-wells in
Pakistan. This work will help to obtain reasonable amount of
energy from ordinary tube well. While designing and
optimizing the turbine it was kept in mind to use standard
accessories so that we may reduce the cost and to facilitate the
fabrication.
Keywords– Pelton Wheel Design Optimization, Portable Power
Plant and Tube-well
I.
INTRODUCTION
n world’s energy generation facilities hydroelectric
generation plays an important role. As in 2010 it was
estimated that hydroelectric generation is about 16% of
global electricity generation [1]. In Punjab, Pakistan there
were approximately more than 9lac tube wells in 2006 with
annual growth 6.12% [2], by installing our proposed turbine
we can obtain 2.8 KW of power per turbine and the total
potential is about 2520 MW. These types of facilities having
generation capacity less than 5KW usually called as Picohydropower plants and these are also cost effective [3]. As in
Pelton wheel turbine more than 90% of water power can be
converted into mechanical power [4].
Hence, in this work 81.5% efficiency is obtained by
changing different parameters again and again. Finally some
recommendations are made in order to get maximum
performance. As tube well does not work 24 hour a day thus
we require some storage facilities so that we may get power
even when the tube well is in off condition. The energy
obtained from the turbine can be used to obtain larger volume
flow rate of water by installing a small pump which in turn
increases the efficiency of our system and decreasing the
irrigation cost. For this the output shaft of the turbine acts as
prime mover for the smaller pump. Secondly this system may
be utilized to generate the electricity for running fans and
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Fig. 1: (Number of tubewells in Pakistan Vs years) [2]
Table 1: (Annual Growth of tubewells (%)) [2]
Annual Growth Rate
of Tubewells
Diesel
Public
Private
Total
Annual Growth (%)
2.96
7.30
6.31
6.12
II.
EXPLANATION
Following are the most important parameters used while
designing. V1, V2 are the absolute velocities of the jet at the
inlet and outlet respectively. The u1, u2 are the peripheral
velocities of the vane at the inlet and outlet respectively. Vr1,
Vr2 are the relative velocities at the inlet and outlet
respectively. Vf1, Vf2 are the Velocities of the flow at the inlet
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INTERNATIONAL J OURNAL OF M ULTIDISCIPLINARY S CIENCES AND ENGINEERING , VOL . 6, NO. 9, S EPTEMBER 2015
and outlet respectively. Vw1, Vw2 are the velocities of the
whirl as the inlet and the outlet respectively.
are the tip
angle at the inlet and the outlet respectively. α, β are the
angles which the absolute velocities makes at the inlet and
outlet.
As head increases power output increases but in this case
increase in head is due to decrease in jet diameter and most
suitable value for head is 12m to get maximum power
efficiently.
B. Jet Diameter vs Head
When the jet diameter decreases the velocity head
increases. And it is required to get maximum velocity head to
obtain maximum output power. So it is proposed that instead
of one, four nozzles of 0.025 m diameter each are suitable to
get maximum head.
If we decrease the diameter further the head increases very
rapidly but this makes the jet diameter too small and affects
the life of pump.
Fig. 2: Bucket inlet and outlet velocity triangles
III.
OPTIMIZATION USING COMPARISON
CURVES METHOD
These calculation were made for the tube well of 14 cm
diameter of outlet pipe and then four jets are installed each of
2.5cm diameter. Means 4cm of diameter not used hence this
will increase the velocity head at the jets.
Design procedure from [5] is adopted and Microsoft Excel
program is written for optimization purpose.
A. Head vs Power Developed
As we are much more interested in power developed. So, if
we have a look at the graph we come to know that the head is
directly proportional to the power developed.
Fig. 4: Jet diameter vs head
C. Jet Diameter vs Power Produced
By decreasing the jet diameter the power produced
increase. Because the head increases as according to the
previous graph. We can conclude from this graph that the
suitable value of the diameter is again 0.025m keeping in
view the power output.
Now from above three graphs we are able to finalize the jet
diameter and it must be 0.025m to get maximum power with
maximum efficiency.
Fig. 5: Jet diameter Vs power output
Fig. 3:
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Head vs power developed
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INTERNATIONAL J OURNAL OF M ULTIDISCIPLINARY S CIENCES AND ENGINEERING , VOL . 6, NO. 9, S EPTEMBER 2015
D. Number of Jets vs Power
F. Angle of Deflection vs Output Power
As for as number of jets are concerned it should be as more
as possible because the increase in number of jets increases
flow rate and velocity gained by the wheel increases. But
technically speaking this happens to a certain limit. After that
limit increase in number of jets decrease the power produced.
It is because the total area of jets becomes large and according
to the equation of continuity velocity of water at the outlet of
the jet decreases due to increase in the total area of the jets.
Hence the maximum number of jets proposed for this vertical
shaft Pelton wheel turbine is 4.
As the angle of deflection increases the power developed
increases. But power developed increase up to some point
after that it begins to decrease. It is because if we increase the
angle of deflection more and more than the water after leaving
the bucket will strike at the back the of next incoming bucket.
This strike will make the wheel to rotate in opposite direction
which in turn will reduce the power.
Fig. 8: Angle of Deflection vs Output Power
Fig. 6: Number of jets vs power
G. Number of Buckets
E. Jet Ratio (M) vs RPM
When we increase the jet ratio i.e., the ratio of diameter of
wheel to the jet diameter, the RPM of the turbine rotor
decreases due to increase in the diameter of the wheel. The
very small value of jet ratio increases the RPM but again it is
not practically possible to decrease the jet ratio from a certain
value. If we do so then the torque which plays a vital role in
power generation decreases also. After plotting different
curves it is decided take this ratio to 13 to get the maximum
efficiency.
Number of buckets has direct relation with power. But too
many buckets make the wheel bulky and deceases the
efficiency to a reasonable extent. Suitable Number of buckets
were determined from table. In this work as selected angle of
deflection is 20o. So 24 buckets are selected. Roughly the
ratio between wheel diameter to the nozzle diameter which is
called jet ratio of 10 is selected [5].
Table 2: Jet ratio and number of buckets [5]
Jet ratio
6
8
10
15
20
25
No. of buckets
17 to
21
18 to
22
19
to
24
22
to
27
24
to
30
26
To
33
IV. MATERIALS SELECTION
The selected material for the runner of the turbine was
manufactured in ASTM CA-6NM soft martensitic cast
stainless steel (G-X4 Cr Ni 13-4, according to the German
DIN designation). Quenched and tempered CA-6NM steel
because of high toughness and due to excellent resistance
against cavitation erosion is widely used for runner castings
for turbomachinery [6] - [9].
V. EFFECT OF JET MISALIGNMENT
Fig. 7: Jet Ratio (M) Vs RPM
Jet alignment is very important because of radial
misalignment of jet decrease the efficiency from 15 to 20
percent [10]. So it is proposed to place the jets in such a way
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INTERNATIONAL J OURNAL OF M ULTIDISCIPLINARY S CIENCES AND ENGINEERING , VOL . 6, NO. 9, S EPTEMBER 2015
that jet strikes in the middle of the bucket and after striking it
converts into to equal streams of water.
VI. ANALYSIS OF TURBINE
The resultant force that a bucket is facing can be calculated
by [5]:
RESULTANT FORCE=
]
The bucket have maximum force concentration at the place
where jet strikes and this trend decreases while going towards
the bucket.
By using this formula is also possible to conduct CFD
(computational fluid dynamic) analysis on the turbine to make
it more efficient. Stress strain analysis can also be conducted
to estimate the life of the turbine.
[3].
Sopian K, Razak J. Pico hydro: clean power from small
streams. Lalaguna, Spain. In: WSEAS renew energy sources;
July 1-3, 2009. p. 414e9.
[4]. Boyle G. Renewable energy—power for a sustainable future.
NewYork: Oxford University Press Inc.; 1996.
[5]. D.S. Kumar (Fluid Mechanics And Fluid Power Engineering).
[6]. Iwabuchi Y. Temper embrittlement of type l3Cr–4Ni cast
steel. Trans Iron Steel InstJpn 1987; 27(3):211–7.
[7]. Tokuda A, Kumada Y, Nakagawa K. Development and results
of a trail production of 13% Cr base cast stainless steel
propeller for ships. JSW Tech Rev1970; 27:3142–52.
[8]. Iwabuchi Y, Sawada S. Metallurgical characteristics of a large
hydraulic runner casting of type 13Cr–Ni stainless steel.
Stainless steel casting, ASTM STP 756; 1982. p. 332–54.
[9]. Larson JA, Fisher R. The effect of heat treatment and melt
practice on the impact properties of CA-6NM steel. AFS Trans
1979; 63:113–26.
[10]. Bryan R. Cobb, Kendra V. Sharp (2012) Impulse (Turgo and
Pelton) turbine performance characteristics and their impact on
pico-hydro installations Renewable Energy.
VII. RESULTS/CONCLUSIONS
In future, putting these portable Pelton wheel turbines at
tube-wells will increase the tube-well efficiency. The
electricity produced by these turbines can be utilized in
running a small pump with the tube-well that will increase the
total flow rate. Here are the details of turbine specifications,
bucket dimensions and output power for the current designed
and optimized portable Pelton wheel turbine for a given tubewell of 14cm outlet pipe diameter.
A. Turbine Specifications
By compiling these results the following specifications for
turbine are recommended.
Vertical axis Pelton wheel turbine
Number of jets
Jet diameter
Jet ratio
Number of buckets
Angle of deflection
4
2.5cm
13
24
20o
B. Bucket Dimensions
Axial width B
Radial length L
Depth T
8 cm
6 cm
2.2 cm
C. Power Output
Power output
2.8 KW
REFERENCES
[1].
[2].
International Energy Agency (IEA). Key world energy
statistics; 2012.
http://s3.amazonaws.com/zanran_storage/www.fao.org/Conten
tPages/93784319.pdf (21-01-2015)
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